Water spot prevention in photographic film



Patented Jan. E6, 1945 WATER SPOT PREVENTION IN PHOTOGRAPHIC FILM Lowell E. Muchler, Charles J. Kunz, and George T. Eaton, Rochester, N. Y., asslgnors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application November 29, 1941, Serial No. 421,038

Claims.

I it to an elevated temperature or a, current of air or both. When the excess water has not been well removed from the film this accelerated drying treatment frequently causes the formation of so-called water spots or physically distorted areas in the emulsion or gelatin layers which are gllajectionable in later viewing or printing of the It is, therefore, an object of the present inven-* tion to provide a method for preventing the water spotting occasioned by the rapid drying of photographic film.

In order to overcome this water spotting tendency obtained in the rapid drying of processed photographic film, we have tried the use of various surface active agents in baths in which the film is immersed after development, fixing, and washing. We have found that whereas some wetting and dispersing agents have little or no effect in preventing water spotting, others are especially useful for this purpose. Many wetting agents were, found to give excessive foam and leave behind undesirable residues on the film which required carefu1 rinsing or squeegeeing for their removal. Thus the compounds marketed under the names Aerosol AY and Aerosol MA which are respectively the diamyl and dihexyl esters of sodium sulfosuccinic acid, when used over a wide range of concentrations, were not satisfactory for these reasons and also because they possessed lower effectiveness as water spot preventatives. We have found, however, that the sulfonated naphthalene wetting and dispersing agents such as the isopropylnaphthalene sulfonates and condensation products of aldehydes and naphthalene sulfonic acids are especially efiective in preventing water spotting. The agents which we pro pose to use are those sold under the trade name Aerosol OS which is the sodium salt of an isopropylnaphthalene sulfonic acid, and Tamol NNO, which is believed to be a condensation product of formaldehyde and a naphthalene sulionic acid neutralized so as to .form the alkali metal salt.

The alkali metal salts of alkylnaphthalene sulfonic acids are sold by the American Cyanamid and Chemical Corporation under various trade names. Sulfonated isopropyl naphthalenes are sold under the trade names Aerosol OS, Vatsol OS and Aquarex. Either the mono-, the di-,.or the tri-isopropylnaphthalene sulfonates may be used but the tri-isopropyl compound gives more foam than the others. Alkyl naphthalene sulfonates having similar properties for our purpose are marketed by the Ciba 00.. Inc., as Invadine N; E. I. Du Pont de Nemours 8; Co., as Alkanol B, Alkanol E, and Alkanol SA; the General Dyestufi Corporation as Corekal A, Nekal A, and Nekal BX; and by the National Aniline and Chemical Corporation as Naccasol A.

The Tamols are sold by Rohm 8: Haas Company. They are believed to be condensation products of an aldehyde such as formaldehyde with naphthalene sulfonic acids by Ulhnann Enzyklopadie der technischen Chemie, 2nd. Auflage (1930), 5. Band, pages 84 and 686 and H. Wagner, Chemiker Zeitung," vol. 46 (1922), page 801. The specific product Tamol NNO, which was used in our tests, is a relatively neutral amorphous solid having no odor. When dissolved in water at low concentrations, it gives an essentially clear colorless solution without odor which does not decompose with standing. More concentrated solutions have a slight yellowish color. A solution of Tamol NNO does not readily foam even with a high degree of agitation and the foam, if any, breaks almost instantaneously. Condensation products of formaldehyde and naphthalene sulfonic acid such as Tamol N, (see H. Wagner, Chemiker Zeitung, voL 46 (1922), page 801) and products known as Neradol N marketed by the I. G. Farbenindustrie, A. (3., when completely neutralized (Ullmann, Enzyklopadie der technischen Chemie, 2nd Auflage (1930) 5. Band,

, page 686) are believed to have properties similar to those of Tamol NNO which is a neutralized product. Neradol ND marketed by the I. G. Farbenindustrie, A. G. is said to consist of completely neutralized Neradol N by G. Grasser, Synthetic Tannins (translated by F. G. A. Enna) (1922) Crosby Lockwood 8! Son, London, page 91. Compare also E. Wolesensky, Technologic Papers of the Bureau of Standards 20: (1925-26) Paper No. 302, pages 11 and 16.

In our method of testing the water spot preventing agents the films used were given a flash exposure such that a low density was obtained. They were developed in the usual Elon hydroquinone developer, fixed in a. hypo fixing bath containing acetic acid, boric acid and potassium alum for 15 minutes, and washed about 20 min-- utes. Immediately after washing, the films were bathed in solutions of the wetting agents under examination for from 1 to 10 minutes, drained a few seconds or squeegeed and then dried. The films were dried in a current of air at 100-l30 F., and the results determined by observation.

The results of our tests indicated that when the film was bathed in a solution of Aerosol OS at a concentration of from 0.5 to 3 grams per liter for from 2 to 10 minutes and rinsed for a few minutes in plain water, the use of a subsequent squeegeeing step was optional. Water spotting was efiectively prevented. If the concentration was increased to about 5 grams per liter, the squeegeeing operation was desirable to prevent the formation of a residue of the wetting agent on the film. Likewise in the case of Tamol NNO where the concentration was greater than 2 or 3 grams per liter it was found desirable to squeegee the film in order to prevent the formation of a residue. In general, the agents which we propose to use may be incorporated in water in a concentration of from 0.5 gram to 5 grams per liter. More or less than these amounts may be used but, in general, a lower amount will not be effective and a higher amount will necessitate careful squeegeeing in order to prevent residue formation on th film.

The following table indicates typical results which we have obtained:

Time of Wetting Concen- Additional agent tration Egg treatment Results and remarks Per cent lilinuies None Streamers" 1 formed. Do Squeegeed Eicessive water spoting. Aerosol S 0.1 2 do No spots; no residue.

Do 0.1 2 None 0. Do 0.05 2 Bqueegeed A few spots. D 0.05 2 None No spots. TamolNNO 0.2 2 Squeegeed- Do.

Do 0.2 2 None No spots; residue. Do O. 1 2 Squeegeed No spots; no residue. Do 0.1 2 None Do. Do 0. 2 Squeegeed Do. Do 0.05 2 None Do.

1 Long water marks produced by streaks of water.

are satisfactory. It was found that solutions of Tamol NNO did not foam as readily as solutions of Aerosol OS nor to the same degree and the Tamol NNO solutions were essentially colorless and clear whereas solutions or Aerosol 08 were slightly turbid.

It is considered that the compounds herein described as suitable for preventing water spots in the drying of film may be packaged as a dry powder or in concentrated solution form for the preparation of dilute solutions for use according to the method herein described. Either the alkali metal sulfonates or the sulfonic acids may be packaged but in the case of the acids, either mixed with the material or in a separate com partment, an alkali metal salt of a relatively weak acid or acid salt such as sodium borates, citrates, or acetate, or an alkali hydroxide sucn. as sodium hydroxide may be included in sufilcient quantity to completely react with the sulfonic acid groups.

It will be understood that the examples and modifications described herein are illustrative only and that our invention is to be taken as limited only by the scope of the appended claims.

We claim:

1. The method of preventing water spots on photographic film during drying, which comprises treating the film, after development, fixing,

' and washing. in a solution of a sulfonated naphthalene selected from the group consisting of an alkyl naphthalene sulfonate and condensation products of an aldehyde and a naphthalene sulfonlc acid, and then drying said film.

2. The method of preventing water spots on photographic film during drying, which comprises treating the film, after development, fixing, and washing, in a solution of an isopropyl naphthalene sulfonate, and then drying said film.

3. The method of preventing water spots on photographic film during drying, which comprises treating the film, aiter development, fixing, and washing, in a solution of a condensation product of an aldehyde and a naphthalene sulfonic acid, and then drying said film.

4. The method of preventing water spots on photographic film during drying, which comprises treating the film, after development, fixing, and washing, in a solution of an isopropyl-naphthalene sulfonate of about 0.1% concentration for about two minutes, and then drying said film.

5. The method of preventing water spots on photographic film during drying, which comprises treating the film, after development, fixing,

' and washing, in a solution of a neutralized condensation product of formaldehyde and a naphthalene sulfonic acid having a concentration of about 0.1% for about two minutes, and then dry- CHARLES J. KUNZ. GEORGE T. EATON. 

